Croft



2 Sheets-Sheet 1..

J. SQBANGROFTL INJECTOR.

No. 322,342. Pafnted Jul -14, 1885.

Inventor:

:4. runs, Pimwutmgnpher. w-l-mn m ac.

o 1 forming a vacuum for the purpose of lifting UNITED STATES PATENTOFFICE.

J. SELLERS BANGROFT, onrHILAnnLrtIIA, PENNSYLVAh IA, ASSIGNOR To WILLIAMSELLERS, or SAME PLACE.

INJECTOR.

SiPECIPICATlION forming part of Letters Patent No. 322,342, dated July14:, 1885.

Application filed February 94,1885. (Model.)

To all whom it may concern:

Be it known that 1, JOHN SnLLERs BAN- CROFT, of the city and county ofPhiladelphia, in the State of Pennsylvania, have invented certain newand useful Improvements in Injectors, of which improvements thefollowing is a specification. i

My invention relates to that class of injectors in which a steamj etapparatus derives the liquid to be moved from a source of supply anddelivers it to a second steam'jet apparatus, which in turn delivers thefluid to the boiler or to another similar jet apparatus, if such befound necessary to overcome the boilenpressu re, and in thisspecification, which describes the construction and operation of twosets of such apparatus, they are hereinafter termed the first and secondsets. In case a third apparatus is used it would be simply a duplicationof the arrangements shown in thefirst and second, and itis thereforeunnecessary to describe more than the first two.

, The successive actions of separate steamjets will be found describedby Giffard in his French Patent, dated May 8, 1858, and in his EnglishPatent, No. 1,665, dated July 23, 1858; but in the instruments describedand shown by Giffard, .as well as in all the modifications of double jet-inj ectors for feeding boilers made since, previous to my invention,it has been the uniform rule for the purpose of starting the injector,when the water has to be lifted or when its temperature exceeds about115 Fahrenheit, to admit the steam to the sets consecutively, so thatthe first set shall be in operation and the column of water flowingthrough thetubes of the second set before steam is allowed to issue fromthe steam-nozzle of the second set. I have discovered that with any ofthe proportions heretofore established between the steam-nozzles and thecombiuingtubes of the first and second sets in such doublejet-injectors, and with the provision for the escape of air and steamfrom these tubes, the admission of steam to the respective sets isnecessarily consecutive, as already stated. For efficiency as aboiler-feeder under all conditions of steam-pressure and ofwater-supply, the first set must be adapted for 'cessive operations.

the supply-water to the instrument, and also for delivering the water,under a pressure usually not exceeding one-third of the boiler-pressure,

-to the second set, and to accomplish these functions it is therecognized rule that in this set the smallest area of the steam-nozzlemust be considerably less than the smallest area of the delivery-tube.On the other hand, the second set being adapted for forcing only, thesmallest area of its steam-nozzle is made large enough to supplement theaction of the first set, so as to deliver the jet of water into theboiler against the boiler-pressure, and if the instrument is to have anyrangeof delivery it must be capable of delivering the water against apress- 11 re higher than that of its boiler-pressure; and

that it may meet these requirements the small- I est area of thesteam-nozzle of this set is made larger than the smallest area of thedeliverytube of this set; but when such injectors are used with highsteamas, for example, in locomotive service-it is impossiblefor thesteam which issues from the steam-nozzle of the second set to passthrough the deliverytube of that setthat is, through an orifice ofsmaller area thanthesteam nozzleitselfwithout establishing aback-pressure in the combining-chamber of the second set greater thanthe first set is capable of overcoming, and under these conditions, ifthere was no way provided by which the steam could be shut off from thesecond set, the water lifted by the first set if it were capable oflifting against such back pressure) could not enter the combining-tubeof the second set, and hence the injector could not be started. Allmakers of double jet-injectors have recognized these conditions and haveprovided valves and stopcocks of various forms for the purpose ofstarting such injectors, these valves, however, be-

ing operated by hand in proper order and with sufficient intervals oftime between the suc- In double jet-in ectors, as heretoforeconstructed, the first set has always been arranged so as to form avacuum by discharging the I steam and entrained air-that is to say, theair that is dragged 0r carriedalong by. the steam through thedelivery-tubeof this set or through an overflow-opening between itscombining and delivery tubes, but little greater in area rco than thedeliverytube, through which the water must be delivered under therequired pressure to the second set. The proportions necessarilyexisting between the areas of the steam-nozzle and deliverytube of thefirst set and the areas of the steam-nozzle, combiningtube, anddelivery-tube of the second set limit the range of steam-pressureswithin which the first set can be used to produce a vacuum. Now, if theboiler-pressure should exceed this limitation, and such pressure shouldbe admitted to the first set, the increased amount of steam issuing fromits steam-nozzle under this higher pressure would be unable'to escapefreely through its overflow-space, and would therefore, produce apressure instead of a vac uum in the water-supply pipe, so that inpractice it has always been found necessary to throttle the steam-supplyat ordinary boilerpressures in order to reduce it within the requiredlimit until the water is lifted, and the necessity for this throttlingoperation has precluded any automatic action of the instrument.

Now, I have discovered that the apparatus may be made automatic underany pressure of steam by increasing the proportionate overflow-space inthe first set, so that it shall be large enough to permit a free escapeof steam and air at the maximum boiler-pressure at which the injectormay be required to operate, and thus to enable the first set to producea vacuum in the water-supply pipe at that pressure; and I have furtherascertained that I can secure the requisite increase by locating anoverflow-opening toward the rear end of the converging combining-tubeand comparatively close to the end of the steam-nozzle; but I have foundthat the velocity ofjet requisite to pro duce the necessary pressureupon the second set could not be attained without concentrating the jetbetween this overflow and the smallest part of the delivery-tube; andthis I have accomplished by providing the combining-tube with anotheroverflow-opening.

The first,which I call the rear onc,is located intermediately betweenthe ends of the combining-tube, as above set forth, gives free escape tothe steam and entrained air, and enables the first set to produce avacuum at any steam-pressure; and the second, which I call the forwardone,is located close to the smallest diameter of the deliverytube,permits the escape of the concentrated jet until this jet has attainedsufficient velocity to enable it to pass through the delivery-tube. Afirst set so constructed will be capable of starting itself, when it isconnected with the water-sup ply, upon the admission of steam to theinstrument, and will continue to deliver water, under proper conditions,to the second set; or if from any cause the jet should be broken thisfirst set will immediately re-esta-blish the jet assoon as thedisturbing cause is removed.

I have also ascertained that the opening in the second set, large enoughin area to permit an escape of the steam from the steam-nozzle of thisset without establishing a back-pressare in its combining-chamber toogreat for the first set to overcome, must be located in thecombining-tube at some point where the cross sectional area of that tubeis greater than the smallest cross sectional area of the steamnozzle.Thus located, the opening will necessarily be at a considerable distancefrom the smallest diameter of the delivery-tube, and while anescapeopeni n g of sufficient area thus located will permit asufficiently free exit of the steam to reduce the back-pressure withinthe required limit, so that the water delivered by the first set canreach and condense the steam issuing from the steanrnozzle of the secondset, yet with that openingaloue the requisite velocity of the jet forovercoming the boilerpressure could not be attained. It becomesnecessary, therefore, as in the first set, to provide in the second seta means for concentrating the jet between such opening thus located andthe smallest diameter of the delivery-tube; and I have met this requirement by providing the combining-tube with another overflow-opening, thefirst or rear one, located intermediately between the ends of the tube,as above set forth, permitting such free escape of steam as to preventthe establishing of a back-pressure on the first set greater than thatset can overcome, and the second or forward opening, located near thesmallest diameter of the delivery-tube, permitting the escape of theconcentrated jet until this jet has attained sufficient velocity toenable it to pass through the delivery-tube against the boilerpressure.This second overflow-opening also assistsin discharging the steam fromthe steamnozzle, and hence supplements the first overflow-opening; butin some casesas, for example, with very high steam or very hot waterevenmore than two overflow-openings may be required in the combining-tubesof both sets.

It will be evident that a douhlejet-injector having its first and secondsets constructed and arranged in the manner above described will becapable of automatically starting itself to deliver water into a boilerso soon as it is put in communication with the steam and water supplies,and consequently, if the jet should be broken by any cause, will becapable of restarting itself as soon as the disturb ing cause isremoved.

I have also discovered that the range of delivery of the doublejet-injectorthat is, the

difference between the maximum and minimum amount of water thrown-can begreatly increased by inclosing one or more of the overflow-openings ofeach set, and preferably all, in one common overflow-chamber having itsoutlet so located that no water can escape there from until after theoverflow-openings of both sets have been submerged, access to the airfrom this chamber being provided for by a check-valve opening outward topermit free escape from the chamber, and excluding any indraft of airwhich would prevent the formation of a vacuum. in the chamber. Thisarrangement allows the water which may overflow from one set to come incontact with and be taken up by the jet passing across theoverflow-openings of the other side, and hence no water will escape fromthe chamber until both sets are overflowing, or until the overflow fromone set becomes too great for the other set to take up. YVith feedwaterof ordinary temper'atu re, the passage of the jet across theoverflow-openings of the second set creates so great a vacuum that alarge amount of water is drawn into the second set from theoverflow-openings of the first set directly-that is to say, withoutpassing through the delivery-tube of that setand this in turn induces anacceleration of the supply through the combining-tube of the first set,so that the total or maximum amount of water delivered to the boiler is,by this conjoint action, very considerably increased. The amount ofwater delivered by this form ofinjector in proportion to the smallestcross-sectional area of the delivery-tube of the second set is vastlygreater than that delivered through the same area by any doublejet-injectorheretofore constructed. When the temperature of thefeed-water is high, the second set overflows slightly, and this surplusis taken up through the overflow-openings of the first set, and therewill be no discharge into the air from the overflow-chamber until thetemperature of the feed-water is increased, so as to cause both thefirst and second sets to overflow. A similar action takes place when thewater-supply is throttled for the purpose of reducing to a minimum theamount of water thrown, and the difference between the maximum andminimum amounts of water delivered by a given instrument or range ofdelivery is much greater than has hitherto been possible. Thisarrangement also makes the action of the injector much more certain andreliable under varied conditions of service, as

any irregularity of action in either set is compensated by the otherset, and no overflow can occur from the chamber until the variation ofwater-supply becomes so great as to exceed. therangeof thisself-regulation. T

It is frequently necessary, especially in locomotive service, to blowsteam back through the water-supply pipe for the purpose of heating thefeed-water, and for this purpose it is necessary to. provide some meansfor holding the overflow check-valve on its seat to prevent the escapeof steam during this heating process. If this valve be closed, as abovede scribed, after the injector is started, it is possible to usefeed-water of higher temperature, and by arranging the overflow check-valve and overflow-chamber in the manner hereinafter described, so asto separate the final overflow in the second set from the commonoverflow-chamber when desired, the temperature of the feed-water may bestill further increased; but it will be observed that when thecheck-valve is thus held shut the injector will not be capable ofrestarting itself until the check-valve is released, and hence thisdevice would be required only under exceptional con ditions.

It is one object of my invention to dispense with movable parts (in adouble jet-injector) for the purpose of starting or regulating theinstrument other than the valves for the admission of steam and water,and at the same time to produce an instrument of the highest efficiencyand the greatest range of delivery; and it is a further object of myinvention while attaining these advantages to produce an instrument thatwill automatically establish its own jet and automatically reestablishit in case the same shall have been broken by any accident short of thebreakage orderangement of any of the parts of the instrument itself;

and to these ends the nature of my improveme'nts in double jet'injectorsconsists in pro.-

viding the first set with overflow-space'in the combining-tube at apoint in the rear of that where the cross-sectional area of thisconverging tube contracts to less than four times the area of thesmallest cross-section of the steamnozzle; and it further consists insupplementing the overflow-space thus provided with an additionaloverflow opening located nearer the smallest diameter of thedelivery-tube.

. It further consists in providing the second set with overflow-space inthe combiningtnbe at a point in the rear of that where thecrossseetional area of this converging tube con-" tracts to an areaequal to that of the'sm'allest' which are inclosed in this chamber shallbe submerged before any water can escape through the overflowcheck-valve.

It further consists in providing means 'for 7 isolating thefinaloverflow in the second set from the other overflows to enable theinjector to take feed-water of the highest temperature.

In the accompanying drawings, which form part of this specification,Figure 1, Sheet 1,

represents a vertical section through an injector embodying theabove-described features of my presentsinvention. Figs. 2, 3, and 4,Sheet 2, are vertical sections through Fig.1 on the lines 2 2 3 3 4 4,respectively, the overflow check-valve being omitted in Fig. 2. Fig.

l 5 is a horizontal section on the line 5 5, showing the Water-supplyand water-regulating valve of the first set. i

In all the figures similar letters indicate similar parts.

The case or body of the injector is made in two parts for convenience ofmanufacture, these parts, A and B, being fastened together by bolts a a,as shown, so as to form a complete case. 0 is the steam connection. D isthe steam-valve, operated by the lever b, and so arranged that thesteam-pressure tends to keep it seated. WVhen this valve is lifted oropened, steam is admitted to the steam-chain ber E, which is common tothe steam-nozzles of both sets.

F is the water connection or supply, from which water is admitted to thewater-chamber G through the valve H, operated by the handwheel 0. Theform of this water-chamber G is more clearly shown in Fig. 5, where itwill be seen that the chamber G extends on one side of the water-supplyF and the lower part of the steamchamber E. vVhen the valve D is lifted,as above described, steam is admitted to the chamber E, and escapesthrough the steam-nozzles I and J. The steam issuing from the nozzle Iblows into the tubes K and K, which constitute the combining-tube, andescapes into the overflow-chamber M, through the rear overflow-opening,(1, between these tubes K and K and the forward overflow-openin g, 6,between K and the delivery-tube L. The steam escapes from thisoverflow-chamber M under a check-valve, f, which allows free exit, butserves to prevent the admission of air. The discharge from this valvetakes place through the passage 9, formed in the body- 13 and continueddown to the outlet h.

' The check-valve f is held firmly on its seat, when necessary, by meansof the screw 1), op erated by the hand-wheel s, and engaging with thescrew-thread formed in the cap a, the screw 1) passing through astuffingbox formed on the upper part of the cap a, as shown in Fig. 1,the object of the stuffing-box being to produce suffieient friction tohold the screw at the top of its stroke, which is its normal positionwhen the injector is used as an automatic instrument. The end of thescrew 1). when at the top of its stroke, allows free lift to the valve fwith its guiding-stem t, and when screwed down may be made to impingeupon the upper end of the stem 15, and so hold the valve f firmly on itsseat, for the purpose described. In Fig. l the stem tof the checkvalve fis shown bored out to receive a plunger, W, and a spiral spring, Y,which rests on the lower end of the recess in the stem 15, and its upperend presses against the cap X, secured firmly to the upper end of theplunger \"V, and so holds the lower enlarged end of the plunger IVfirmly up against the lower part of the valve f, and the whole deviceacts in the same manner as a solid check-valve, being lifted by pressurewithin the overflowchamber M, and falling to its seat and closing toprevent the admission of air when a vacuum is produced in the chamber M,as hereinbefore described.

The cap X extends above the end of the hollow stem 2, and when the screwp is run down to hold the valve f shut it first impinges 011 the cap Xand, pushing it down, compresses the springY and forces the enlarged endof f firmly on its seat.

The nozzle I, combining-tube K and K, and overflow-openings d and e areso proportioned that the steam issuing from the nozzle I entrains theairfrom the chamber G into the tube K, from which this entrained air andsteam escape through the overflow-opening (Z into the chamber M. Thesteam which accumulates in the chamber 0, as hereinbefore described,blows back through the conduit N and delivery-tube L and escapes intothe Y chamber M, principally through the overflowopening (2, which thusrelieves the steam-jet 'issuin from the nozzle I from thecounterpressure of the jet issuing from the delivery tube L, which wouldotherwise almost completely prevent the formation of a vacuum, and thiscombined action produces a vacuum in the water-supply chamber G, so thatif the ,valve H is opened the water from a well or other source ofsupply will be drawn into the cham ber G through the water connection F.To have the proportions for insuring this operation and producing thenecessary vacuum in the chamber G, it is essential that theoverflow-opening (I should. be located, as shown in the drawings,at apoint in the combining-tube K K, where the cross-sectional area of thistube is at least four times the area of the smallest crosssection of thesteam-11ozzleI;and that the overflow-openings d and 6 should be largeenough in area to give a free escape to the entrained air, and to thesteam issuing from the nozzle I and the delivery-tube L at the highestboiler-pressure at which the injector may be required to operate, thusinsuring the formation of a vacuum at such pressure. Such avacuum willbring the water into contact with the steam-jet issuing from the nozzleI, and at this point, instead of entrained air, and steam, water andsteam enter the tube K, and this jet of water and steam combineddischarges into the overflow-chamber M, partly through theoverflow-opening d from the tube K,- and partly through theoverflow-opening e from the tube K. The converging tube K and overflow econcentrate the jet and increase its velocity in the tube K until theoverflow at d ceases, and the combined concentrated jet passes throughthe tube K, overflowing at e, and its velocity continues to increaseuntil the overflow at e ceases, when the combined concentrated jet willhave acquired suffleient impetus to carry it across the overflow-opening6 into the deliverytube L against the steampressure established in thechamber 0.

An overflow-opening near the small part of the delivery -tube' could notalone be made large enough in area to give asufficiently free dischargefor the entrained air and steam without cutting off the combining tubeto such extent as to deprive it of the power of concentrating the jetsufficiently to enter the delivery-tube. On the other hand, an extensionof the converging part of the-deliverytube toward the steam-nozzle, withan opening located nearer to the steamnozzle and large enough in area topermit a free discharge a sufficiently free escape for the steam issuingin the opposite direction from the deliverytube L, the conjointoperation of the two overflows (Z and 6, therefore, could not beaccomplished by one single overflow however cated, for it will be seenthat while the two overflows have severally distinct functions toperform, each overflow co-operates with and supplements the other.

From the delivery-tube the jet passes through the conduit N to thecombining or water chamber 0 of the second set. The steam issuing fromthenozzle J of the second set passes through the tubes P and P, which"constitute the combining-tube, and escapes through therearoverflow-opening, 70, between the tubes P and P, and the forwardoverflowopening, Z, between P and the delivery-tube B into the chamberM, which is common to the overflows from both the first and second sets.The steam from the nozzle J also fills the water-chamber O andestablishesa certain pressure there and produces a discharge of steamback through the conduit N and delivery-tube L of the first set, asbefore described,

and the combining-tube P P and overflowopenings 70 and Z of the secondset areso porportioned to the steam-nozzle I and to the combining-tube KK and delivery-tube L of the first set that thispressure in the chamber7 0 will never be too great with any steam- 7 pressure in chamber 0 fromexceeding this pressure to prevent the water delivered by the first setfrom reaching the steam issuing from the nozzle J. To have theproportions for insuring this operation and preventing the limitation,it is essential that the overflowopening It should be located, as shownin the drawings, at a point in the combining-tube P P where thecross-sectional area of this tube is larger than the area of thesmallest crosssuch freedom that any back-pressure which u may beproduced in chamber 0 will alwaysbe less than the first set is capableof overcoming. The water delivered by the first set will reach andcombine with the steam issuing from the nozzle J and pass through thetube P, and this jet of steam and water combined discharges intotheoverflow-chamber M, partly through the overflow-opening k fromthe'tube P, and partly through the overflow-opening Z from the tube P.The converging tube P and overflow Z concentrate the jet and increaseits velocity in the tube P until the overflow at k ceases, and thecombined concentrated jet passes through the tube P overflowing at Z,and its velocity continues to increase until the overflow at Z ceases,when the combined concentrated jet will have acquired sufficient impetusto carry it across the overflow-opening Z, through the delivery-tube R,and into the boiler through the connection S. An overflow-opening nearthe small part of the delivery-tube could not alone be madelarge enoughin area to give a sufficiently free discharge for the steam in this setwithout cutting off the combining-tube to such an extent as to depriveit of the power of concentrating the (which I secure by the opening 70',located as already described,) so as to reduce the back pressure withinthe required limit, would not give the necessary concentration andvelocity to the jet to enable it to pass through the delivery-tube'R,and the conjoint operations of the two overflows 7c and Z, therefore,could not be accomplished by one single overflow however located, for itwill be seen that in the second set, as in the first set, while thesetwo overflows have severally distinct functions to perform, eachcooperates with and supplements the other, and that they conjointlyco-operate with the openings inthe first set, so that by their combinedaction the instrument will automatically establish and reestablish itsown jet, as presently described.

A check-valve, m, is placed at the end of the injector near theconnection S, as shown, to prevent escape of waterfrom the boiler whenthe injector is not working.

' The check-valve f is placed at the top of the overflow-chamber M, sothat any water which may overflow from either the first or second setswill be retained in the chamber M until after the overflow-openings fromboth sets have been submerged. This arrangement allows the water whichmay overflow from one set to be taken up through the overflow-openingsof the other set, and hence no water will escape through the check-valvef until both sets are overflowing, or the overflow from one set becomestoo great for the other set 'to take When the temperature of theadmitted wa ter rises to too high a point, water will escape from theoverflow chamber through the Valve f as soon as the pressure in theoverflowchamber M becomes greater than the atmospheric pressure. Theproportions of the tubes are such,however, that the injector will feedwater into the boiler with considerable pressure in chamber M when thevalvef is held shut by the screw 1), as before described, and hence thetemperature of the feed-water may be thus considerably increased; butunder these circumstances the injector will not be automatic, and shouldthe jet be broken will be unable to reestablish its jet until thecheck-valve f is released. The delivery-tube R and the discharging endof the combining-tube P are inclosed in a chamber or case, T, formed inthe body B. This case T communicates freely with the overflow-chamber Mthrough the opening V when the screw 1? is atthe top of its stroke, asshown in Fig. 1, and the relative action of the overflow-openings willbe as hereinbefore described. \Vhen, however, it becomes desirable forany purpose to feed water of a higher'temperature than the injector iscapable of operating with antomatically, and the valve f is closed bymeans of the screw. 1), the piston XV fills the opening V and separatesthe case T from the chamber M, so that the water which would otherwiseoverflow from the final overflowopening Z is prevented from entering thechamber M, and consequently from reaching the overflow-openings of thefirst set and producing a pressure there which would break the jet. Thisdevice is only required when the temperature of the feed-watcr isexceptionally high, and for all ordinary purposes of boiler feeding theplunger WV may be omitted and the stem t be made solid.

The'proportion of the; steam-nozzles and combining tubes relative to theoverflowspaces of the respective sets is such that the first set isalways capable of producing a vacuum, and hence of lifting the water,and that the second set cannot establish a back-pressure in chamber 0sufficient to prevent the first set from delivering water to thesecondsteam-jet issuing from the nozzle J. These proportions of thecombining-tubes and overflows further facilitate the rapid and certainformation of the jet as soon as steam and water are admitted to theinjector.

If desired, the steam-valve D may be arranged with a supplemental valveclosing the steam-nozzle J ,or with a cylindrical extension entering acylindrical seat in the nozzle J, so

- that when the valve D is raised a short distance from its seat steammay be admitted to the first nozzle, I, only. This arrangement isdesigned to avoid the waste of steam issuing from the nozzle J, and isonly desirable when the injector has to liftits watera greatheight. Assoon as water appears at the overflow h the steam-valve D is furtheropened, so as to lift the supplemental valve or withdraw the cylindricalplug from the nozzle J, as the case may be, and the steam issuing from Jwill instantly unite with the water, and the injector will go to work,and everything will also be in proper condition for the automatic re-establishment of the injector, if the jet should be broken from any cause.

It is not essential that the overflow-openings of either set should bemade annular, as shown in the drawings, between the ends of separatetubes, for the combining and delivery tubes of either set may be formedin one piece, and the necessary overflow-space pro vided by perforatingthem with a series of holes of sufficient aggregate area located in theconverging tube at any point where its cross-section is sufficientlylarge, as hereinbefore described, for the purpose of the first overflow,and an additional series of corresponding holes located just before thesmallest part of the delivery-tube for the purpose of starting theconcentrated jet, as above described, or the annular overflow openingsmay be supplemented by a series of holes, if desired.

Having now described the nature and objects of my invention, what Iclaim therein as new, and desire to secure by Letters Patent, 1s- 7 1.In a double jet-injector, a first set of jet apparatusprovided withoverflow-space in the combining-tube at a point in the rear of thatwhere the cross-sectional area of this converging tube contracts to lessthan four times the area of the smallest cross-section of thesteamnozzle, substantially as and for the purposes set forth.

2. In combination with overflow-space in the first set of jetapparatus,located in the combining-tube at a pointin the rear of thatwhere the cross sectional area of this converging tube contracts to lessthan four times the area of the smallest crosssection of thesteam-nozzle,

an additional overflow-opening in this con1- biningtube nearer thesmallest diameter of the delivery-tube, the combination being andoperating substantially as described.

3. In a double j et-inj ector,a second set of j et apparatus providedwith overflow-space in the combining-tube at a point in the rear of thatwhere the cross-sectional area of this converging .tube contracts to anarea equal to that of the smallest cross-sectional area of thesteamnozzle, substantially as and for the purposes set forth.

4. In combination with overflow-space in the second set of jetapparatus,located in the combining-tube at a point in the rear of thatwhere the cro'sssectional area of this converging tube contracts to anarea equal to that of the smallest cross-sectional area of thesteamnozzle, an additional overflow-opening in this combining-tubenearer the smallest diameter of the delivery-tube, the combination beingand operating substantially as described.

5. In combination with the first set, constructed and operatingsubstantially as described, the second set correspondingly provided withtwo overflow-openings respectively located and arranged therein, as setforth, the two sets being combined and oper- 322,842 to i 7 ating incombination, substantially as described, so that the instrument willautomatically establish and reestablish its own jet, as set forth.

6. An overflow-chamber common to one or more of the overflow-openingslocated in each set of j et apparatus, substantially as described, andfor the purposes set forth.

7. I11 combination with an overflow-chamber common to one or more of theoverflowopenings of each set of jet apparatus, an overflow-check valveso arranged that all of the overflow-openings which are connected withthe overflow-chamber shall be submerged be fore any water can escapethrough the over- J. SELLERS BANOROFT.

Witnesses:

J AS. 0. BROOKS, JNo. H. SOHWAOIL

